System and Method for Producing Homogenized Oilfield Gels

ABSTRACT

A system for producing homogenized oil field gel including a power unit, a control system, a feed tank, a hopper, and a piping assembly that includes inlet and outlet manifolds, centrifugal pumps, and metering devices for filling the feed tank and handling a discharge of oilfield gel. The system further includes a powder hydration component and liquid chemical equipment. The method for producing homogenized oil field gel includes a guar powder procedure including a controlled sequence for starting and stopping a venturi mixer in a hydration unit. The method for producing homogenized oil field gel further includes a liquefied gel concentrate procedure including a metering and chemical injection procedure for mixing a liquefied gel concentrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a continuation of U.S. patentapplication Ser. No. 13/705,946, filed Dec. 5, 2012, which claimspriority to U.S. Provisional Patent Application No. 61/566,958, filedDec. 5, 2011, each of which is hereby incorporated by reference in itsentirety for all purposes.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This application is not the subject of any federally sponsored researchor development.

THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT

There have been no joint research agreements entered into with any thirdparties.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The embodiments of the present invention relate to a system and methodfor producing high quality homogenized oilfield gels from traditionalliquefied gel concentrates (LGC) and guar gum powder.

2. Description of the Related Art

Prior art systems for generating oilfield gels generally rely on LGCsdue to the difficulty of hydrating guar gum powder, where, if eachparticle of powder is not thoroughly wetted, unwanted agglomerates (“gelballs”) can form in the mixture, reducing the overall yield andrequiring high energy, high shear processing, which is usuallyunsuccessful.

There are several advantages to using dry guar powder, including cost,environmental, and transport benefits. LCGs were previously created bysuspending guar (or another polymer) in petroleum based products so thatthey could be pumped and blended with water. Due to environmentalconcerns stemming from the use and disposal of fracturing fluids, thepetroleum products were replaced with natural mineral oils. However,these natural mineral oils are in short supply, are costly, and anyfluid used for suspension adds a significant amount of weight to thetotal materials needing to be delivered to the site. Dry guar powderrequires nothing for suspension, thus it is less expensive, weighs less,and is more easily transported.

There exists a need for dry powder handling and hydration systems thatproduce functional oilfield gel “on-the-fly” without recirculation,agglomerates, or damaging high shear processes.

SUMMARY OF THE INVENTION

The embodiments of the present invention include a system for producingoil field gel including a power unit including an engine, pumps, and allrequisite auxiliary components for providing hydraulic power. The systemfor producing oil field gel further includes a control system, a feedtank comprising a plurality of chambers, and a hopper. The system forproducing oil field gel further includes a piping assembly that includesinlet and outlet manifolds, centrifugal pumps, and metering devices forfilling the feed tank and handling a discharge of oilfield gel. Further,the system for producing oil field gel includes a powder hydrationcomponent with a venturi mixing system, and liquid chemical equipment.

Another embodiment of the present invention is directed to a method forproducing oil field gel including: metering dry guar powder using anagitated hopper and a metering dispenser; dispensing known volumes ofguar powder to a pickup funnel; hydrating the guar powder using ahydration tank, where the hydration tank includes a reservoir of freshwater; supplying water from the reservoir by a first centrifugal pumpinto a first chamber; delivering water to an eductor device by a secondcentrifugal pump creating a vacuum via the eductor device forcing enoughwater through the system; closing a vacuum interrupter valve therebycreating a vacuum in a powder conveyance line; delivering powder to thepickup funnel by the dispenser; hydrating the powder creating gel; anddischarging the gel into a second chamber of the hydration tank.

The embodiments of the present invention further include a hydrationunit including an agitated hopper, a metering dispenser, a hydrationtank, an eductor device, at least one centrifugal pump, a pressure gaugeor transducer, a vacuum interrupter valve, a powder conveyance line, apick-up funnel, at least one chamber, and an integrated sump.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred features of the embodiments of the present invention aredisclosed in the accompanying drawings, wherein similar referencecharacters denote similar elements throughout the several views, andwherein:

FIG. 1 is a side view of equipment for producing oilfield gels accordingto an embodiment of the present invention;

FIG. 2 is a flow path diagram of a system for producing oilfield gelsaccording to an embodiment of the present invention;

FIG. 3 is a perspective view of a system for producing oilfield gelsaccording to an embodiment of the present invention; and

FIG. 4 is a side view of the bi-level floor of the hopper in crosssection of a system for producing oilfield gels according to anembodiment of the present invention.

DETAILED DESCRIPTION

The embodiments of the present invention will now be described morefully hereinafter with reference to the accompanying drawings, in whichpreferred embodiments of the invention are shown. This invention may,however, be embodied in many different forms and should not be construedas limited to the illustrated embodiments set forth herein. Rather,these illustrated embodiments are provided so that this disclosure willbe thorough and complete and will convey the scope of the invention tothose skilled in the art.

In the following description, like reference characters designate likeor corresponding parts throughout the figures. Additionally, in thefollowing description, it is understood that terms such as “top,”“bottom,” “upper,” “lower,” “first,” “second” and the like, are words ofconvenience and are not to be construed as limiting terms.

This application also hereby incorporates by reference the followingprior art U.S. patents and published patent applications that includesubject matter related to the aspects of the embodiments of the presentinvention as described herein: U.S. Pat. No. 7,048,432 (“Method andApparatus for Hydrating a Gel for Use in Subterranean Formation”; issuedate of May 23, 2006); U.S. Pat. No. 7,794,135 (“Dry Polymer HydrationApparatus and Methods of Use”; issue date of Sep. 14, 2010); U.S. PatentApplication Publication No. 2008/0264641 (“Blending Fracturing Gel”);U.S. Patent Application Publication No. 2004/0008571 (“Apparatus andMethod for Accelerating Hydration of Particulate Polymer”); U.S. Pat.No. 5,382,411 (“Apparatus and Method for Continuously Mixing Fluids”;issue date of Jan. 17, 1995); U.S. Pat. No. 5,334,788 (“Reaction ofSubstrate Compounds with Fluorine in an Eductor”; issue date of Aug. 2,1994); U.S. Pat. No. 7,794,135 (“Dry Polymer Hydration Apparatus andMethods of Use”; issue date of Sep. 14, 2010); U.S. Pat. No. 5,426,137(“Method for Continuously Mixing Fluids”; issue date of Jun. 20, 1995);U.S. Pat. No. 5,344,619 (“Apparatus for Dissolving Dry Polymer”; issuedate of Sep. 6, 1994); U.S. Pat. No. 5,447,394 (“Automatic FlushingApparatus for a Hydrator”; issue date of Sep. 5, 1995); U.S. Pat. No.6,817,376 (“Gel Hydration Tank and Method”; issue date of Nov. 16,2004); and U.S. Pat. No. 5,190,374 (“Method and Apparatus forContinuously Mixing Well Treatment Fluids”; issue date of Mar. 2, 1993).

An embodiment of the present invention includes onboard dry powderhandling and hydration systems that produce functional oilfield gel“on-the-fly” without recirculation, agglomerates, or damaging high shearprocesses. The capability of the embodiments of the present inventionwill improve this portion of fracturing operations worldwide.

For market acceptance considerations, in an embodiment of the presentinvention, the ability to produce oilfield gel from LGCs is maintained.

The embodiments of the present invention include a power unit. The powerunit in an embodiment of the present invention includes a diesel engine,hydraulic pumps, and all requisite auxiliary components. The power unitin an embodiment of the present invention provides system hydraulicpower.

The embodiments of the present invention include a feed tank. The feedtank in a preferred embodiment of the present invention includes a180-barrel capacity steel tank (or the like) for making and storingfunctional oilfield gel. One of ordinary skill in the art willunderstand that the feed tank is not limited to a 180-barrel tank, butmay be smaller or larger taking into account many factors includingapplication. The feed tank in an embodiment of the present inventionincludes a clean water chamber for more precise metering, and encouragescleaning of the venturi mixer and components (to empty the unit out atthe end of a job, tank 1 is emptied through the venturi mixer, whichwill encourage cleaning).

As shown in FIG. 1, for mixing the liquefied component, retaining theability to work with the LGC is made possible through the plurality ofchambers that are included in the feed tank. The embodiment shown inFIG. 1 includes six tanks, where the tanks provide dwell time to givethe gel an adequate time period to hydrate. Chamber 1 is dedicated asthe clean chamber in an embodiment of the present invention.

The embodiments of the present invention include a hopper. The hopper ina preferred embodiment of the present invention includes a 10,000 lb.capacity powder tank (or the like) with agitators, a sump, and aconveyance screw specifically designed for metering and dispensing dryguar powder. One of ordinary skill in the art will understand that thehopper is not limited to a 10,000 lb. capacity powder tank, but may besmaller or larger taking into account many factors includingapplication. One of ordinary skill in the art will also understand thatother means for metering other than the conveyance screw may be providedin the embodiments of the present invention. Additionally, the shape ofthe hopper is not limited to what is shown in the accompanying figures.Examples of agitators include, but are not limited to, paddles,vibrators, rotating devices, and the like.

The embodiments of the present invention include a piping assembly. Thepiping assembly in an embodiment of the present invention includes inletand outlet fluid manifolds, centrifugal pumps, and metering devices forfilling the feed tank and handling discharge of oilfield gel. As shownin FIG. 1, the piping assembly may include a pressurized fresh watersupply pipe 10, a centrifugal pump 11, and a fresh water supply pipe 12.

The embodiments of the present invention allow for the use of drypowdered gel, rather than slurry or liquid gel. The powder hydrationcomponent group allows for a dual slurry/powder or powder unit. Theembodiments of the present invention include a powder hydrationcomponent group. The powder hydration component group in an embodimentof the present invention includes a venturi mixing system that usespressurized water for creating a vacuum and wetting a dry polymer. Thepowder hydration component group in an embodiment of the presentinvention includes a vacuum break valve, pressure transducer or switch,centrifugal pump, pneumatic conveyance line, and pickup funnel.Additionally, the powder hydration component group may include a flowmeter.

The embodiments of the present invention include a liquid chemicalequipment group. The liquid chemical equipment group in an embodiment ofthe present invention includes chemical pumps, metering devices, andhosing for adding liquid chemicals to a functional gel or for making afunctional gel from liquid concentrate.

The embodiments of the present invention may include a platform andcabin. The platform and cabin in an embodiment of the present inventionprovide a comfortable environment for operators, and a safe pathway fromthe controls to the feed tank, powder hopper, and mixing devices. FIG. 3shows an entire system according to a preferred embodiment of thepresent invention. In FIG. 3, the operator cabin is shown as element 1,the walkway/access platform is shown as element 2, and the manifoldsystem is shown as element 3.

The embodiments of the present invention also may include severalprocedures for producing homogenized oilfield gels. In particular, anembodiment of the present invention includes a guar powder procedure.The guar powder procedure in an embodiment of the present inventionincludes a controlled sequence (which may be handled by a programmablelogic controller, or relay logic) for starting and stopping the venturimixer. This sequence may be handled automatically as a means of avoidinga failure mode of the mixer.

An embodiment of the present invention includes a LGC procedure. The LGCprocedure of an embodiment of the present invention includes a meteringand chemical injection procedure for mixing LGC, other chemicals, and/orwater at the correct ratios.

The embodiments of the present invention each contribute to theprocedures that are created to ensure correct chemical ratios and toavoid mixer failure modes. In an embodiment of the present invention, anautomatic control system (programmable control system) allows anoperator to achieve the desired chemical ratios.

Other features of the embodiments of the present invention include aventuri mixing system. Additionally, the embodiments of the presentinvention include a control system, an interface, and graphical controlinterface (such as Stewart & Stevenson's “ACCUFRAC”). The embodiments ofthe present invention may also include a guar powder hopper, a revisedfeed tank with clean water chamber, a power unit concept, and a chemicaladditive components and processes.

Additional detail of an embodiment of the present invention and theprocess and related flow path of an embodiment of the present inventionwill now be described.

The hydration unit of the embodiments of the present invention isdesigned to produce high quality, homogenized oilfield gels from bothtraditional, liquefied gel concentrates (LGC) and guar gel powder. Priorart systems for generating oilfield gels generally rely on LGCs due tothe difficulty of hydrating guar powder; if each particle of powder isnot thoroughly wetted, unwanted agglomerates (“gel balls” of “fisheyes”) usually form in the mixture which reduce the overall yield andrequire usually unsuccessful high energy, high shear processing.Further, LCGs typically use either a hydrocarbon-based carrier fluid ormineral oil for polymer suspension. Mineral oil adds significant cost tothe production of oilfield gel, and hydrocarbon-based fluids requirecareful handling and disposal because they are hazardous to theenvironment. Another advantage of the embodiments of the presentinvention is the transportation and storage cost. For example, thepowder can be stored indefinitely if stored correctly, while the slurryhas a shelf life. Additionally, transportation cost with powder is lessthan with slurry. Another advantage of the embodiments of the presentinvention is the time to hydrate the powder as opposed to the slurry (nohydrocarbon based molecules need to be removed from the powder thatwould block water for hydrating).

Onboard dry powder handling and hydration systems of the embodiments ofthe present invention produce functional, biodegradable oilfield gel“on-the-fly” without recirculation, agglomerates, or damaging high shearprocesses.

The equipment and processes for producing oilfield gels from powderedguar gum are described herein, and examples are shown in FIGS. 1 and 2.FIG. 1 shows an agitated guar powder hopper 1, a metered auger powderdispenser 2, a powder pickup funnel 3, a vibrator 4, a powder pneumaticconveyance hose 5, a hydration tank 6, an eductor hydration device 7, avacuum interrupter valve 8, a pressure transducer 9, a pressurized freshwater supply pipe 10, a centrifugal pump 11, a fresh water supply pipe12, a metered fresh water tank inlet pipe 13, a flow meter 14, and acentrifugal pump 15.

Dry guar is stored and precisely metered by an assembly comprised ofitems 1 and 2 depicted in FIG. 1. Item 1 is an agitated hopper designedto promote positive flow of guar powder to the metering dispenser 2. Inan embodiment of the present invention, the hopper 1 is designed with anobstruction free interior to prevent powder accumulation, agitationpaddles to prevent bridging and to force powder into the dispenser, anda split-level conical floor to maximize paddle effectiveness. Thesplit-level conical floor may include an agitator (e.g., a sweeper or aplurality of sweepers on each level). See FIG. 4.

An obstruction free interior is made possible by moving the structuralmembers to the outside. The top of the hopper 1 in an embodiment of thepresent invention features a manual fill hatch if the operator is notable to fill the tank pneumatically, and the sides of the hopper 1 areequipped with hinged doors if the hopper 1 needs to be emptied manually.

In an embodiment of the present invention, the dispenser 2 utilizes ametering auger screw to dispense known volumes of guar powder to thepickup funnel 3. The volumetric flow rate of powder can be controlled bycomputer or manually by manipulating the angular velocity of the augershaft. One of ordinary skill will appreciate that the screw augerdelivery system may be replaced by other known delivery systems inembodiments of the present invention.

The hydration tank 6 in an embodiment of the present invention ispreferably a six-chamber, 200 barrel capacity tank (or the like)designed for preparing oilfield gels either from LGCs or guar powder.One of ordinary skill in the art will understand that the tank is notlimited to a 200-barrel tank, but may be smaller or larger taking intoaccount many factors including application. When using guar powder, thefirst chamber serves as a reservoir of fresh water. Water is supplied bya centrifugal pump 15, metered by flowmeters 14, and discharged into thefirst chamber using an inlet pipe 13. The centrifugal pump 15 is theonly source of fresh water in the system.

In an embodiment of the present invention, the eductor device 7functions by forcing enough water through the device to create aninternal vacuum. This volumetric flow rate of water is a known constant,and is delivered to the eductor device 7 via a second centrifugal pump11. In most cases, the volumetric flow rate of water required by theeductor device 7 will be less than the total required gel flow rate. Inthis condition, the extra fresh water spills over from the first chamberinto the second gel chamber, thereby diluting the gel and homogenizingdownstream. If less water is drawn into 12 then comes out of 13, thenthe water just spills over the weir in the two chambers. The figuresshow a weir or divider between the chambers, which may have spill overor spill under capacities. For example, every other divider may have aspill over weir, or spill under weir.

The pressure drop across the eductor device 7 is monitored by a pressuregauge or transducer 9. When a sufficient vacuum is present, the vacuuminterrupter valve 8 can be closed, thereby creating a vacuum in thepowder conveyance line 5.

The system is designed to create enough of a vacuum to convey all powderdelivered to the pickup funnel 3 by the dispenser 2.

As powder is ingested by the eductor device 7, all particles arehydrated and gel is discharged into chamber two of the hydration tank 6.As previously mentioned, it may be combined with additional fresh waterfrom chamber one for dilution. The hydration tank can be equipped withpaddles to promote good circulation, and the shape of the paddles may besuch to prevent shearing the material.

As seen from the flow path diagram in FIG. 2, in an embodiment of thepresent invention, fluid will ultimately pass through at least sixchambers before being discharged from the tank. In an embodiment of thepresent invention, an integrated sump is built into chamber six, wherethe gel can either be pumped or gravity fed into a manifold for ultimatedischarge from the hydration unit. Additionally, paddles may be present.

The embodiments of the present invention may also include auxiliarysubsystems. The auxiliary subsystems include a custom dry hopper capableof storing 10,000 lbs of material and designed for the physicalproperties of guar powder. Additionally, the auxiliary subsystems mayinclude the intuitive, Stewart & Stevenson, LLC “ACCUFRAC” graphicalcontrol interface, and a 180 bbl feed tank designed to promote cleaningand maintenance of mixing equipment. In the embodiments of the presentinvention, the other onboard systems may be the systems that are commonto prior art hydration units, and a person skilled in the art wouldreadily understand what is included in these systems.

The embodiments of the present invention also include features to ensurethat the right amount of powder with the right amount of water. Apreferred embodiment of the present invention includes a system forweighing the hopper. For example, the hopper has a load cell on oneside, and a hinge point on the other side. Reading the load cell overtime allows for measuring the amount of gel delivered. This is a backupof typical volumetric delivery.

“Guar powder” or “guar gum powder” as used throughout this applicationincludes guar powder as well as any other type of gel powders includingnatural powder or polymer powder or otherwise synthetic powder or thelike in which gels are to be formed thereof.

An example of the start-up and shutdown procedures according to apreferred embodiment of the present invention will now be described.

Startup Procedure:

1. Fill the feed tank;

2. Turn on dry gel mixing system centrifugal pump (FIG. 1, Item 11);

3. Wait for 750 gallons/minute rate through the dry mix system;

4. Close the vacuum break valve (FIG. 1, Item 8); and

5. Begin delivering dry powder to the pickup funnel (FIG. 1, Item 3)according to desired recipe.

Shutdown Procedure:

1. Stop delivering powdered gel to the pickup funnel (FIG. 1, Item 3);

2. Open the vacuum break valve (FIG. 1, Item 8);

3. Flush powder mixing system for at least 2 minutes; and

4. Stop the dry gel mixing system centrifugal pump (FIG. 1, Item 11).

What is claimed is:
 1. A system for producing oil field gel comprising:a power unit comprising an engine and one or more pumps; a controlsystem; a feed tank comprising a plurality of chambers; a hopper; apiping assembly comprising inlet and outlet manifolds, centrifugalpumps, and metering devices for filling the feed tank and handling adischarge of oilfield gel; and a powder hydration component comprising aventuri mixing system.
 2. The system according to claim 1, wherein thepower unit comprises a diesel engine and hydraulic pumps.
 3. The systemaccording to claim 1, wherein the feed tank comprises a fresh waterchamber.
 4. The system according to claim 1, wherein the hoppercomprises a powder tank including agitators, a sump, and a conveyancescrew for metering and dispensing dry guar powder.
 5. The systemaccording to claim 1, wherein the powder hydration component comprises:a venturi mixing system that uses pressurized water for creating avacuum and wetting a dry polymer; a vacuum break valve; a pressuretransducer or switch; a centrifugal pump; a pneumatic conveyance line;and a pickup funnel.
 6. The system according to claim 1, wherein theliquid chemical equipment comprises: chemical pumps; metering devices;and hosing for adding liquid chemicals to a functional gel or for makinga functional gel from a liquid concentrate.
 7. The system according toclaim 1, further comprising a platform and cabin.
 8. The systemaccording to claim 1, wherein the hopper comprises agitation paddles anda split-level conical floor.
 9. The system according to claim 1, whereinthe hopper comprises a manual fill hatch.
 10. The system according toclaim 1, wherein the hopper comprises hinged doors on its sides so thatit may be emptied manually.
 11. A method for producing oil field gelcomprising: metering dry guar powder using an agitated hopper and ametering dispenser; dispensing known volumes of guar powder to a pickupfunnel; hydrating the guar powder using a hydration tank, wherein thehydration tank comprises a reservoir of fresh water; supplying waterfrom the reservoir by a first centrifugal pump into a first chamber;delivering water to an eductor device by a second centrifugal pumpcreating a vacuum via the eductor device forcing enough water throughthe system; closing a vacuum interrupter valve thereby creating a vacuumin a powder conveyance line; delivering powder to the pickup funnel bythe dispenser; hydrating the powder creating gel; and discharging thegel into a second chamber of the hydration tank.
 12. The methodaccording to claim 11, further comprising: a guar powder procedurecomprising a controlled sequence for starting and stopping a venturimixer in a hydration unit, the hydration unit comprising: the agitatedhopper; the metering dispenser; the hydration tank; the eductor device;at least one centrifugal pump; a pressure gauge or transducer; thevacuum interrupter valve; the powder conveyance line; the pick-upfunnel; at least one chamber; and an integrated sump; and a liquefiedgel concentrate procedure comprising a metering and chemical injectionprocedure for mixing a liquefied gel concentrate.
 13. The methodaccording to claim 14, wherein the hydration unit further comprises aventuri mixing system.
 14. The method according to claim 14, wherein thehydration unit further comprises a control system.
 15. The methodaccording to claim 14, wherein the controlled sequence is handled by aprogrammable logic controller.
 16. The method according to claim 14,wherein the agitated hopper is a guar powder hopper, and wherein thehydration unit further comprises a revised feed tank with a clean waterchamber, a power unit, and a chemical additive.
 17. The method accordingto claim 13, wherein the dispenser comprises a metering auger screw todispense known volumes of guar powder.